PRE-MIX BURNER ASSEMBLY FOR LOW NOx EMISSION FURNACE
A burner assembly according to aspects of the disclosure includes a burner surface carried by a burner, the burner surface extending outward from a front side of the burner, a housing coupled to the burner on a side opposite the front side of the burner, a gasket disposed between the burner and the housing, a thermally anisotropic protective covering located on the front side of the burner and surrounding a perimeter of the burner surface, and an igniter positioned adjacent to the burner surface.
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This application is a continuation of U.S. patent application Ser. No. 15/723,284, filed on Oct. 3, 2017. U.S. patent application Ser. No. 15/723,284 is incorporated herein by reference. This patent application incorporates by reference for any purpose the entire disclosure of U.S. patent application Ser. No. 15/723,340, filed on Oct. 3, 2017. This patent application incorporates by reference for any purpose the entire disclosure of U.S. patent application Ser. No. 15/723,564, filed on Oct. 3, 2017 which is now U.S. Pat. No. 10,711,997.
TECHNICAL FIELDThe present disclosure relates generally to furnaces utilized with heating, air conditioning, and ventilation (“HVAC”) equipment and more specifically, but not by way of limitation, to pre-mix furnace assemblies utilizing a pre-mix burner assembly having a gasket and a protective covering to prevent damage to the pre-mix burner assembly.
BACKGROUNDThis section provides background information to facilitate a better understanding of the various aspects of the disclosure. It should be understood that the statements in this section of this document are to be read in this light, and not as admissions of prior art.
Furnaces are common equipment in many commercial and residential HVAC systems. Operation of such furnaces typically includes the controlled combustion of a hydrocarbon fuel such as, for example, propane or natural gas, in the presence of atmospheric air. Theoretically, complete stoichiometric combustion of the hydrocarbon fuel yields carbon dioxide (CO2), water vapor (H2O), Nitrogen (N2), and heat energy. In practice, however, complete stoichiometric combustion of the hydrocarbon fuel rarely occurs due to factors including, for example, combustion residence time and hydrocarbon fuel/air mixture ratio. Incomplete combustion of the hydrocarbon fuel yields combustion byproducts including, for example, carbon monoxide (CO) and various nitrous oxides (NOx). CO and NOx are generally regarded to be environmental pollutants and emissions of byproducts such as CO and NOx are commonly limited by federal, state, and local regulations. NOx, in particular, has recently been the subject of aggressive pollution-reducing agendas in many areas. As a result, manufacturers of furnaces and related HVAC equipment have undertaken efforts to reduce emission of NOx.
SUMMARYA burner assembly according to aspects of the disclosure includes a burner surface carried by a burner, the burner surface extending outward from a front side of the burner, a housing coupled to the burner on a side opposite the front side of the burner, a gasket disposed between the burner and the housing, a thermally anisotropic protective covering located on the front side of the burner and surrounding a perimeter of the burner surface, and an igniter positioned adjacent to the burner surface.
A burner assembly according to aspects of the disclosure includes a burner surface carried by a burner plate, the burner surface extending outward from a front side of the burner surface, a housing coupled to the burner plate on a side opposite the front side of the burner plate, a gasket disposed between the burner and the housing, the gasket being formed of a single layer of material, and an igniter positioned adjacent to the burner surface.
A furnace assembly according to aspects of the disclosure includes an intake manifold fluidly coupled to a supply line, a burner assembly fluidly coupled to the intake manifold, the burner assembly having a burner surface carried by a burner, the burner surface extending outward from a front side of the burner, a housing coupled to the burner on a side opposite the front side of the burner, a gasket disposed between the burner plate and the housing, a thermally anisotropic protective covering located on the front side of the burner and surrounding a perimeter of the burner surface, wherein a thermal conductivity across a length and across a width of the thermally anisotropic protective covering is higher than a thermal conductivity across a thickness of the thermally anisotropic protective covering, an igniter positioned adjacent to the burner surface, a burner box assembly thermally exposed to the burner assembly, and a heat-exchange tube fluidly coupled to the burner box assembly.
This summary is provided to introduce a selection of concepts that are further described below in the detailed description. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it to be used as an aid in limiting the scope of the claimed subject matter.
The disclosure is best understood from the following detailed description when read with the accompanying figures. It is emphasized that, in accordance with standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of various features may be arbitrarily increased or reduced for clarity of discussion.
Various embodiments will now be described more fully with reference to the accompanying drawings. The disclosure may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.
During operation of a furnace, production of NOx is typically dependent upon factors including, for example, hydrocarbon fuel/air mixture ratio and residence time. In general, combustion of a hydrocarbon fuel/air mixture (e.g. greater than approximately 50% excess air) is desired. Additionally, a well-mixed hydrocarbon fuel/air mixture with a low residence time is desirable for low NOx production and emission. “Residence time” refers to a probability distribution function that describes the amount of time a fluid element could spend inside a chemical reactor such as, for example, a combustion chamber.
Most residential and commercial HVAC equipment utilize induced draft “atmospheric” burners. Atmospheric burners are characterized by an initial mixing of atmospheric air and the hydrocarbon fuel. This is typically accomplished by entraining the atmospheric air into the hydrocarbon fuel stream via, for example, a venturi or other similar device. This initial entrainment of atmospheric air into the hydrocarbon fuel stream is commonly referred to as “primary air.” Atmospheric burners typically operate with a rich hydrocarbon fuel to primary air mixture and thus require an additional source of air commonly referred to as “secondary air” to fully complete the combustion process, which results in a relatively large flame volume. The large flame volume increases combustion residence times, which allows further NOx production to occur. In atmospheric burners, combustion typically occurs in the presence of excess air. Excess air helps to cool off the products of combustion and spreads the combustion process over a larger area. The flame is typically drawn by a combustion air blower into a heat exchanger. This contributes to longer combustion times which results in increased production of NOx.
Another type of furnace utilizes a pre-mix burner. Pre-mix burners are typically fan powered, which allows the hydrocarbon fuel/air mixture ratio to be carefully controlled to eliminate the requirement for secondary air to complete the combustion process. Pre-mix burners operate with a lean hydrocarbon fuel/air mixture and often exhibit short blue flames. Pre-mix burners exhibit short reaction zones and high burning velocities. This leads to short residence time and high combustion efficiency, which limits NOx production and emission.
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Conditional language used herein, such as, among others, “can,” “might,” “may,” “e.g.,” and the like, unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain embodiments include, while other embodiments do not include, certain features, elements and/or states. Thus, such conditional language is not generally intended to imply that features, elements and/or states are in any way required for one or more embodiments or that one or more embodiments necessarily include logic for deciding, with or without author input or prompting, whether these features, elements and/or states are included or are to be performed in any particular embodiment.
The foregoing outlines features of several embodiments so that those skilled in the art may better understand the aspects of the disclosure. Those skilled in the art should appreciate that they may readily use the disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the disclosure, and that they may make various changes, substitutions and alterations herein without departing from the spirit and scope of the disclosure. The scope of the invention should be determined by the language of the claims that follow. The term “comprising” within the claims is intended to mean “including at least” such that the recited list of elements in a claim are an open group. The terms “a,” “an,” and other singular terms are intended to include the plural forms thereof unless specifically excluded.
Claims
1. A burner assembly comprising:
- a burner comprising a burner aperture;
- a burner surface disposed across and extending through the burner aperture and protruding outward from the burner;
- a housing coupled to the burner;
- a gasket disposed between the burner and the housing, wherein the housing is directly coupled to a fuel intake manifold; and
- an igniter positioned adjacent to the burner surface.
2. The burner assembly of claim 1, comprising:
- a thermally anisotropic protective covering directly coupled to a front side of the burner and surrounding a perimeter of the burner surface.
3. The burner assembly of claim 2, wherein the thermally anisotropic protective covering is formed of a graphite material.
4. The burner assembly of claim 1, wherein the gasket is formed of a single layer of material.
5. The burner assembly of claim 2, wherein a thermal conductivity across a length and across a width of the thermally anisotropic protective covering is higher than a thermal conductivity across a thickness of the thermally anisotropic protective covering.
6. The burner assembly of claim 1, wherein a first side of the gasket is directly coupled to the burner and a second side of the gasket opposite the first side is coupled to the housing.
7. The burner assembly of claim 1, wherein the burner comprises flanges formed around a periphery of the burner and are bent rearwardly away from the burner surface.
8. The burner assembly of claim 7, wherein the flanges increase strength and rigidity of the burner.
9. The burner assembly of claim 8, wherein the flanges create separation between the burner surface and the housing facilitating even distribution of fuel/air mixture entering through a fuel aperture.
10. A furnace assembly comprising:
- an intake manifold fluidly coupled to a supply line;
- a pre-mix burner assembly fluidly coupled to the intake manifold, the pre-mix burner assembly comprising: a burner comprising a burner aperture; a burner surface disposed across and extending through the burner aperture and protruding outward from the burner; a housing coupled to the burner; a gasket disposed between the burner and the housing, wherein the housing is directly coupled to a fuel intake manifold; and an igniter positioned adjacent to the burner surface.
11. The furnace assembly of claim 10 comprising:
- a burner box assembly thermally exposed to the pre-mix burner assembly; and
- a heat-exchange tube fluidly coupled to the burner box assembly.
12. The furnace assembly of claim 10, wherein the pre-mix burner assembly comprises:
- a thermally anisotropic protective covering directly coupled to a front side of the burner and surrounding a perimeter of the burner surface.
13. The furnace assembly of claim 12, wherein the thermally anisotropic protective covering is formed of a graphite material.
14. The furnace assembly of claim 10, wherein the gasket is formed of a single layer of material.
15. The furnace assembly of claim 12, wherein a thermal conductivity across a length and across a width of the thermally anisotropic protective covering is higher than a thermal conductivity across a thickness of the thermally anisotropic protective covering.
16. The furnace assembly of claim 10, wherein a first side of the gasket is directly coupled to the burner and a second side of the gasket opposite the first side is coupled to the housing.
17. The furnace assembly of claim 10, wherein the burner comprises flanges formed around a periphery of the burner and are bent rearwardly away from the burner surface.
18. The furnace assembly of claim 17, wherein the flanges increase strength and rigidity of the burner.
19. The furnace assembly of claim 17, wherein the flanges create separation between the burner surface and the housing facilitating even distribution of fuel/air mixture entering through a fuel aperture.
20. A furnace assembly comprising:
- an intake manifold fluidly coupled to a supply line;
- a pre-mix burner assembly fluidly coupled to the intake manifold, the pre-mix burner assembly comprising: a burner comprising a burner aperture; a burner surface disposed across and extending through the burner aperture and protruding outward from the burner; a housing coupled to the burner; a gasket disposed between the burner and the housing, wherein the housing is directly coupled to a fuel intake manifold; an igniter positioned adjacent to the burner surface; and a thermally anisotropic protective covering directly coupled to a front side of the burner and surrounding a perimeter of the burner surface.
Type: Application
Filed: Oct 20, 2021
Publication Date: Feb 17, 2022
Patent Grant number: 11598557
Applicant: Lennox Industries Inc. (Richardson, TX)
Inventors: Eric PEREZ (Hickory Creek, TX), Randal POIRIER (The Colony, TX), Eric CHANTHALANGSY (Grand Prairie, TX), Steven SCHNEIDER (Plano, TX), Glenn W. KOWALD (Carrollton, TX), Ian BURMANIA (Rockwall, TX)
Application Number: 17/505,886